1. Field of the Invention
This invention relates generally to an optical quantizer and, more particularly, to an optical quantizer that employs a chain of optical thresholding devices positioned in a propagation path of an optical input beam that provide a series of indicator signals indicative of the intensity of the input beam.
2. Discussion of the Related Art
Advances in signal processing technology, including the need for greater processing speeds increased channel bandwidths and improved transmission reliability, has resulted in a steadily growing focus on the optical domain and the vast potential that lies therein with respect to these parameters. However, optical technology, as compared to electrical and radio frequency based technology, lacks the necessary technical sophistication in many areas. Particularly, the desire for high-speed, large-bandwidth processing devices employing digital optics has been hampered by the lack of many basic optical devices and technologies readily available in the RF domain.
Optical analog-to-digital (A/D) converters are one such device that has not heretofore met basic design requirements. Current digital optical systems rely on digital conversion in the electrical/RF domain. This requires conversion back and forth between the optical and RF domains that are slower, have more loss and are noisier than conversions in the optical domain only. An optical device that converts an optical analog signal to an optical digital signal with little or no reliance on RF technology would reduce system complexity and provide for high speed and large bandwidth processing advances. Optical quantizers that take an analog-optical input signal and generate a coded, quantized output that corresponds to the intensity of the input signal is a necessary and important part of optical A/D converters.
U.S. patent application Ser. No. 09/133,138, filed Aug. 11, 1998, titled "Upper-Folding Successive-Approximation Optical Analog-To-Digital Converter and Method of Performing Conversion," and assigned to the assignee of this application, is directed to an optical A/D converter that provides an analog-to-digital conversion within the optical domain without the need to subtract optical signals. Further, U.S. patent application Ser. No. 09/345,295, filed herewith titled "Delayed Pulse Saturable Absorber-Based Downward-Folding Optical A/D," also assigned to the assignee of this application, is directed to an optical A/D converter that also provides an analog-to-digital conversion within the optical domain that employs the use of optical thresholding devices and saturable absorbers.
What is needed is an efficient, cost effective and reliable optical quantizer that has application to be used in an optical A/D converter. It is therefore an object of the present invention to provide such an optical quantizer.